Obstructive Sleep Apnea (OSA) is a relatively common disorder with a prevalence of 2 percent to 4 percent among middle-aged adults. Several epidemiological studies have linked OSA with increased morbidity and mortality. Polysomnography, a time-consuming and expensive test, is the gold standard for the diagnosis of this disorder. Alternative less expensive and convenient strategies, based on self-reported symptom surveys, have been proposed as initial screens for this disorder. However, most of these techniques have been developed on limited of patients and have not undergone rigorous validation. Moreover, outcome measures such as the clinical diagnosis have not been adequately addressed. At The Johns Hopkins Sleep Disorders Center, a self-administered symptom questionnaire designed to assess a variety of sleep-related symptoms, has been in use for the last four years. The primary objective of the current proposal is to use the existing questionnaire responses from more than 2000 patients to construct (Specific Aim number 1) and ultimately validate (Specific Aim number 2 and number 3) a simple and more concise diagnostic tool, The Hopkins Sleep Survey, for the identification of individuals with OSA.